Although the fibrin adhesion enjoys increasing success in many areas of surgery, it has not become fully established in nerve anastomosis. It was in this area particularly that significant advantages were expected. As the fibrin clot dissolved prematurely, however, and dehiscences ensued, antifibrinolytic substances had to be added to the adhesive. Fibroses occurred frequently as a result, which to date encumber nerve adhesive. We examined Faktor XIII for his fibrosis-inducing effect because both presently available fibrin adhesives contain unphysiologically high concentrations of it. We were able to establish that Factor XIII possesses a fibrosis-promoting effect.